Electrolytic apparatus for producing hydrated iron oxide

ABSTRACT

ELECTRIC CURRENT IS FLOWN THROUGH THE ELECTROLYTIC CELL WHILE RAW WATER IS BEING FED THERETO.   AN ELECTROLYTIC ELECTRODE DEVICE, WHICH COMPRISES AN INSOLUBLE ANODE PLATE FORMED WITH A PLURALITY OF LIQUID HOLES AND POSITIONED IN THE LOWER PART OF AN ELECTROLYTIC CELL, BAR IRON PROVIDED SUBSTANTIALLY VERTICALLY ON SAID ANODE, CATHODE MEMBERS LOCATED PARALLELLY AND ABOVE THE TOP OF SAID BAR IRON, AND MEANS TO INSULATE ELECTRICALLY SAID BAR IRON AND CATHODE FROM EACH OTHER, WHEREBY AN

Sept. 18, 1973 AK|TQ NAKAGAWA ET AL 3,759,814

ELECTROLYTIC APPARATUS FOR PRODUCING HYDRATED IRON OXIDE Filed Aug. 4,1971 3 Sheets-Sheet 2 INVEN'I'ORS M: 1M magnum BY 0 P 29" mmanvnKl'ncHiRO vsmsuao (75m Mn Attorney:

ELECTROLYTIC APPARATUS FOR PRODUCING HYDRATED IRON OXIDE 3 Sheets-Sheet{5 Filed Aug. 4, 1971 FIG. 7

23C 5 b 23a United States Patent ELECTROLYTIC APPARATUS FOR PRODUCINGHYDRATED IRUN OXIDE Akito Nakagawa, Kenji Ueda, Hironari Tanigawa, and

Keiichiro Ishiguro, Nagasaki, Japan, assignors to Mitsubishi JukogyoKabushiki Kaisha, Tokyo, Japan Filed Aug. 4, 1971, Ser. No. 168,858Claims priority, application Japan, Aug. 14, 1970,

Int. Cl. B01k 3/04 U.S. Cl. 204--275 4 Claims ABSTRACT OF THE DISCLOSUREAn electrolytic electrode device, which comprises an insoluble anodeplate formed with a plurality of liquid holes and positioned in thelower part of an electrolytic cell, bar iron provided substantiallyvertically on said anode, cathode members located parallelly and abovethe top of said bar iron, and means to insulate electrically said bariron and cathode from each other, whereby an electric current is flownthrough the electrolytic cell while raw water is being fed thereto.

This invention relates to an electrolytic electrode device forcondensers which are used on thermal plants, chemical plants, ships andthe like.

Heretofore, much of the cooling pipes for such plants and the like havebeen made of corrosion-resistant copper or copper alloy. They havedisadvantages, however, in that, depending on the service conditions andenvironments, they may be corroded, thereby shortening the life of thecooling line as a whole. Especially when the condenser uses a largevolume of sea or river water as the medium for its cooling pipes, thecorrosion of the cooling line can bring the operation of the entiresystem to a stopsThe causes of the corrosion are many and diversified;they include, for example, the potential difference between oxygen anddifferent metals, or battery action which leads to local electrolysisand corrosion, dezincification, impact of running water which results inimpact corrosion, impurities which effect a deposit attack, and stresseswhich also corrode the metals.

In order to avoid the corrosion of the types above described, means tointroduce ferrous sulfate into cooling water thereby to form ananti-corrosive lining on the inner wall surface of the cooling pipes,and means to supply iron ions to cooling water through electrolysis ofiron by an electrolyzer as shown in FIG. 1 were recently proposed andhave met wide acceptance.

The former, or the means of forming a protective lining of ferroussulfate introduced into the cooling water, is disadvantageous becauseferrous sulfate comprises anhydrous salt and many diiferent hydroussalts aside from a heptahydrate, all with different iron contents, and,unless it is strictly controlled, the chemical to be added cannot bemaintained in a proper proportion to the water volume. If the chemicalproportion is too large, the chemical will deposit to excess on theinner wall of the cooling pipe, thus forming an excessively thickanti-corrosive lining for adequate heat conduction, or the chemicalthrown into the cooling water may directly cause a corrosion.

The latter, orthe means of supplying iron ions to cooling water throughthe electrolysis of iron by an electrolyzer as shown in FIG. 1, also hasshortcomings as will be described below. Referring to FIG. 1, numeral 1indicates a tubular electrolytic cell body, for example, in the form ofa cylinder with a substantially vertical axis. The cell body .1 isprovided with fittingflauges 2a, 2b around the upper and lower' endopeningsiIt is made of a syn- Patented Sept. 18, 1973 thetic resin oriron plates, formed with a rubber lining in the case of iron plates forthe dual purpose of corrosion resistance and insulation. The lowerflange 2b of the cell body 1 is superposed with an insoluble anode plate4 formed with a plurality of liquid holes 3a and a loadsupporting plate5 also formed with a plurality of liquid holes 3b of the same shape assaid liquid holes 3a and in the positions matching the same, and afunnel-shaped end cover 6 is attached to the superposed plates.

Usually the insoluble anode plate 4 is made of platinum, lead-silveralloy, magnetic oxide of iron, platinumplated titanium or the like, andthe load-supporting plate 5 is made of a synthetic resin or the like.The funnelshaped cover 6 is provided with an inlet pipe 7 for coolingwater as shown at the upper left part thereof, and is also provided witha normally closed drain pipe 8 at the bottom. Over the insoluble anodeplate 4 is placed a carbon plate 9 for protecting the anode plate. Thecarbon plate 9 is formed with liquid holes 3c at points corresponding tothe holes 3a. Above the carbon plate 9, or inside the electrolytic cellbody 1, there are contained a plurality of scrap iron pieces 10 ofdiameters larger than those of the liquid holes 3a, 3b, 30. To the upperflange 2a of the cell body 1 is attached a cathode plate 11, for examplein the form of an iron grid, which is perforated with a plurality ofliquid holes, and an inverted-funnelshaped cover 13 formed with anelectrolyte outlet pipe 12 at the top is secured to the upper flange 2athrough the cathode 11. The anode plate 4 and the cathode plate 11 areconnected, respectively, to the positive and negative poles of anelectric source (not shown).

In operating the electrolyzing apparatus of the construction abovedescribed, a DC voltage is applied between the anode 4 and the cathode11 while introducing raw water for cooling, for example sea Water, intothe cell through the inlet pipe 7. The current passes through theinsoluble anode 4, carbon plate 9, and scrap iron pieces 10 and reachesthe cathode 11. During this period the scrap iron pieces 10 are meltedin the manner as represented by the Formula A below in proportion to thecurrent applied. As a result, the electrolyte containing Fe++ flows outof the outlet pipe 12, and the inner surface of a copper or copper alloycooling pipe (not shown) in communication with the outlet pipe 12 isanti-corrosively lined with the hydrated iron oxide (FeOOI-I) asrepresented by the Formulas B and C below. Thus, as the scrap ironpieces 10 melt,

Fe Fe+++2e (A) and, as the Fe++-containing electrolyte flows out throughthe cooling pipe,

with the result that the inner surface of the cooling pipe is coatedwith an anti-corrosive film of hydrated iron oxide (FeOOH).

However, with the apparatus above described, the operation for anextended period of time tends to cause dropping of the scale, as ofmagnesium hydroxide, Mg(OH)2, and calcium carbonate, CaCO from thecathode 11 and accumulation of the scale on the scrap iron pieces 10,even allowing part of the deposited scale to gain entrance into thespaces among the scrap iron pieces 10 and thereby choke the flowpassages. The rate of cooling water which flows into the cooling pipedecreases to disadvantage. Moreover, the electrolysis with the currentapplied as above causes melting of the upper surface of the scrap ironpieces 10 nearest to the cathode 11, and therefore the liquid resistancebetween the scrap iron pieces 10 and the cathode increases and thecurrent is thereby reduced. This, combined with the resistance by thescale accumulated on the scrap iron pieces 10, makes it necessary toincrease the current in order to obtain a desired Fe++ amount.Accordingly, the cell voltage of the electrolytic cell 1 must beincreased as represented by the curve D of FIG. 2, with a consequentincrease of the power consumption. This necessitates control throughfrequent opening of the electrolytic cell 1 to maintain the desiredconditions. Further, in case when the electrolytic apparatus shown inFIG. 1 is installed, for example, on a ship, Where it is subjected tovibration due to the rolling and pitching of the vessel, the insolubleanode 4 tends to be damaged thereby.

The present invention has been prefected with the foregoing in view. Itcomprises, in essence, an insoluble anode plate formed with a pluralityof liquid holes and positioned in the lower part of an electrolyticcell, bar iron provided substantially vertically on said anode, cathodemembers located parallelly and above the top of said bar iron, and meansto insulate electrically said bar iron, and means to insulateelectrically said bar iron and cathode members from each other, wherebyan electric current is flown through the electrolytic cell while seawater is being fed thereto. According to this invention, an electrolyticelectrode device is provided whose power consumption is considerablysaved through the reduction of the electrolytic cell voltage and inwhich the clogging of the flow passages with any scale from the cathodeis prevented and the electrolytic cell is capable of use in a closedstate for an extended period of time, even in a place subject tovigorous rocking or vibration.

These and other objects, advantages and features of the presentinvention will become apparent from the following detailed descriptiontaken in conjunction with the accompanying drawings, in which:

FIG. 1 is a vertical sectional view of a conventional electrolyticelectrode device;

FIG. 2 ls a characteristic curve showing changes of the electrolyticcell voltage with time for electrolysis in da s;

FIG. 3 is a vertical sectional view of an embodiment of the invention;

FIG. 4 is a transverse sectional view of the embodiment of FIG. 3;

FIG. 5 is a perspective view of the detail of the anode assembly ofanother embodiment;

FIG. 6 is a transverse sectional view of the second embodiment;

FIG. 7 is a vertical sectional view of the anode assembly of stillanother embodiment.

The first embodiment of the invention will now be described withreference to FIGS. 3 and 4. As shown in FIG. 3, numeral 21 indicates atubular electrolytic cell body in the form, for example, of a cylinderwith a substantially vertical axis. The cell body 21 is provided withfitting flanges 22a, 22b around the upper and lower end openings. It ismade of a synthetic resin or iron plates, formed with a rubber lining inthe case of iron plates for the dual purpose of corrosion resistance andinsulation. The lower flange 22b of the cell body 21 is superposed withan insoluble anode plate 24, for example of platinum, formed with aplurality of liquid holes 23a and a load-supporting plate 25 also formedwith a plurality of liquid holes 23b of the same shape as said liquidholes 3a and in the positions matching the same, and a funnel-shaped endcover 26 is attached to the superposed plates. The funnel-shaped endcover 26 is provided with a normally closed drain pipe 27, and on oneside of the cell body 21 is provided an inlet pipe 28 for sea water forcooling use, for example at right angles to the axis of the tank body.Over the in soluble anode plate 24 is placed a carbon plate 29 forprotecting the anode plate 24. The carbon plate 29 is formed with liquidholes 23c at points corresponding to the holes 230. Above the carbonplate 29, there are placed a plurality of bar iron 30 accommodated inthe cell body 21. The bar iron 30 is larger in diameter than the liquidholes 23a, 23b, and 230.

To the upper flange 22a of the cell body 21 is attached a cathode plate31, for example in the form of an iron grid, which is formed with aplurality of liquid holes, and an inverted-funnel-shaped cover 33 formedwith an electrolyte outlet pipe 32 at the top is secured to the upperflange. To the cathode 31 are attached a plurality of cathode bars 31adirected vertically downward around the bar iron 30. The lower ends ofthe cathode bars 3101 are kept short of contact with the carbon plate21, and are insulated with a synthetic resin or the like to avoidconsumption of the carbon plate 29 due to any localized high current.Between the cathode bars 31a and the bar iron 30 is disposed aninsulating cylinder 35 which is open at the top and the bottom and isformed with a plurality of liquid holes '34 throughout the shell. Thisinsulating cylinder 35 is made, for example, of a synthetic resin andprotects the bar iron 30 from falling into contact with the cathode bars31a thereby forming a short-circuit. The anode plate 24 and the cathodeplate 31 are connected, respectively, to the positive and negative polesof an electric source (not shown). I

With the construction above described, the apparatus operates in thefollowing manner. When a DC voltage is applied between the anode 24 andthe cathode 31 while introducing sea water for cooling into the cellthrough the inlet pipe 28, the current passes through the insolubleanode 24, carbon plate 29, bar iron 30, and liquid holes 34 of theinsulating cylinder 35, and reaches the cathode bars 31a. At the sametime, a part of the current flows through the top opening of theinsulating cylinder 35 to the cathode 31. In the meantime, the bar iron30 is melted in proportion to the current supplied, in the manner wellknown to the art and according to the Formula A above. The electrolytethat contains iron ions as represented by the formula Fe Fe++}+2e flowsout through the outlet pipe 32 and the drain pipe 27, so that the innerwall surfaces of copper or copper alloy cooling pipes (not shown)connected, respectively, to the pipes 27, 32 are anti-corrosively coatedwith hydrated iron oxide (FeOOH) in accordance with the Formulas B andC. Because the cathode 31 has liquid holes above the bar iron 30 and thebar iron 30 in turn is opposed to a plurality of bar cathodes around itscircumference, there is no possibility of a part of the iron in theupper part of the cell 21 being rapidly melted away as in a conventionalcell. As a whole the bar iron 30 melts uniformly with no such sharpincrease in the liquid resistance between the cathode 31 and the anode24 as is the case with ordinary arrangements. Further, if the scale ofmagnesium hydroxide, Mg(OH)- and the like comes off from the cathode, ithas no eifect whatsoever upon the liquid resistance between the bar iron30 and the bar cathodes 31a, and the resistance remains unchanged. Theuse of bar iron 30 precludes the clogging of the flow passage with thescale removed from the cathode. Therefore, it is not necessary to openthe electrolytic cell 21 after many hours of operation to eliminate thescale droppings as required with a conventional cell. For this reasonand by the abovementioned reason of no increase in the liquidresistance, the cell voltage of the electrolytic cell-21 draws a lowercurve B as shown in FIG. 2 than the comparative curve D of aconventional apparatus, thus indicating a considerable saving of powerconsumption. The provision of the insulating cylinder 35 between thecathode bars 31a and the bar iron 30 avoids short-circuiting in betweenin case the bar iron should fall against the bar electrodes, and makesit possible to install the apparatus in a place subject to vigorousvibration, as on a ship. These are extremely practical advantages.Moreover, because the free ends of the cathode bars 31a are electricallyinsulated, no localized high current flows between the cathode bars andthe carbon plate 29, and therefore the carbon plate 29 is protectedagainst wear due to oxidation.

While the embodiment above described uses platinum as the insolubleanode 24, it should be apparent of course to those skilled in the artthat platinum may be replaced by a lead-silver alloy, magnetic oxide ofiron, platinumplated titanium or the like. Also, the inlet pipe 29 forthe sea Water for cooling use which is provided in the direction atright angles to the axis of the electrolytic cell 21 may be provided insome other way, for example in the direction tangential to the cell 21,in which case an additional advantage of effective removal of scale fromthe cathodes 31, 31a will be attained because the sea water introducedinto the cell 21 will flow therein in the form of a swirling flow.

In FIGS. and 6 there is shown another embodiment of the presentinvention. It differs from the first embodiment in the following points.Throughout the figures illustrating the two embodiments, like numeralsindicate like parts and the description of those parts will be omittedhereunder. In the second embodiment, a plurality of bar iron groups 43each consisting of a plurality of bar iron elements 41 bound togetherwith an insulating frame 42 are held substantially vertically or uprighton an insoluble anode 24 through a carbon plate 29, between adjacentliquid holes 23a of the anode 24, by means of clamps 421; provided atthe bottom of the insulating frames 42. In brief, the second embodimentis characterized in that the bar iron groups 43 are secured upright bymeans of clamps 42b so that they are held between the edges of theadjacent liquid holes 23a (23b, 23c) and 23a (23b, 23c), and that thecathode bars 31a are provided along the liquid holes 23a, 23b, and 230as shown in FIG. 6. Thus, by dint of the insulating frames 42 whichsecure them in position, the bar iron groups 43 will have less chance offalling by rocking or vibration and provide greater safety than thearrangement of the first embodiment. Moreover, because the cathode bars31a are provided along the liquid holes 23a, 23b, and 23c, the scalewhich once deposited on the cathode bars 31a and has come off therefromcan be easily discharged from the cell via the liquid holes 23a, 23b,and 23c.

FIG. 7 illustrates a third embodiment of the invention. Description ofthe parts bearing the same reference numerals as those of the two otherembodiments will be omitted hereunder. This third embodiment differsfrom the others in the following points. It uses as the bar ion 30 aplurality of iron tubes, each of which receives an insulating cylinder51 which in turn accommodates a cathode bar 53. The insulating cylinder51 is formed with a plurality of liquid holes 52 and has a lowerextension 51b for fixing use which is fitted securely in the superposedliquid holes 23c, 23a, and 23b, respectively, of a carbon plate 29, aninsoluble anode plate 24, and a loadsupporting plate 25. The cylinder isopen at the top and bottom ends.

As described hereinabove, the present invention provides an arrangementcomprising, in essence, an insoluble anode plate formed with a pluralityof liquid holes and positioned in the lower part of an electrolyticcell, bar iron provided substantially vertically on said anode, cathodemembers located parallelly and above the top of said bar iron, and meansto insulate electrically said bar iron and cathode members from eachother, so that an electric current is flown through the electrolyticcell while sea Water is being fed thereto. With this construction, thereis no possibility of the flow passage being clogged by the scale whichhas come olf from the cathode after prolonged operation of theapparatus, and the electrolytic cell can be used in an enclosed statefor a long period of time. Moreover, the bar iron is enabled to meltuniformly throughout by the action of the cathode members provided alongits length and thereabove, and therefore any sharp increase of theliquid resistance between the cathode and bar iron is prevented.Further, because the insulation is interposed between the cathode andbar iron thereby precluding short-circuiting, the electrolytic electrodedevice according to the: invention is extremely safe against rocking andvibration.

What is claimed is:

1. An electrolytic electrode device comprisin an electrolytic cell body,an insoluble anode plate having a plurality of liquid openings disposedin a lower portion of said cell body, a carbon plate superimposed onsaid anode plate for protecting the latter, bar iron substantiallyvertically disposed on said superimposed carbon plate and anode plate,cathode means in said cell body having parts thereof disposed parallelto said bar iron and parts thereof disposed above said bar iron, andmeans to electrically insulate said bar iron and cathode means from eachother, whereby an electric current is passed through the device as seawater flows therethrough.

2. An electrolytic electrode device according to claim 1 wherein saidcarbon plate has a plurality of openings aligned with said plurality ofopenings in said anode plate, said bar iron comprising a plurality ofbar iron groups each including a plurality of bar iron elements, saidbar iron groups being disposed generally upright on said superimposedcarbon plate and anode plate between said aligned openings.

3. An electrolytic cell according to claim 1 wherein said bar iron is inthe form of a plurality of iron tubes, said insulating means includingat least one insulating cylinder disposed about said iron tubes, atleast some of said parts of said cathode means being accommodated insaid cylinder, said cylinder being formed with a plurality of liquidopenings in its circumferential wall.

4. An electrolytic cell according to claim 1 wherein said carbon plateand anode plate are disposed on a support plate.

References Cited UNITED STATES PATENTS 1,335,210 3/1920 VonWurstemberger 204196 3,448,035 6/1969 Serfass 204-272 2,801,697 8/1957Rohrback 204-275 FOREIGN PATENTS 1,104,078 2/ 1968 Great Britain 204-272JOHN H. MACK, Primary Examiner W. T. SOLOMON, Assistant Examiner US. Cl.X.R.

